Make sure the fuel lines off the back of the TBI aren't hitting the
cab where they go over the back of the intake manifold.
--
Old Crow "Yol Bolson!"
'82 FLTC-P "Miss Pearl"
'95 YJ Rio Grande
BS#133, SENS, TOMKAT, MAMBM

Did you rebuild the fuel pressure regulator?
They can hammer off of the seat sometimes, especially if they were 4.3
injectors, which are of a lesser Lbs/Per Hr.
RK
PS
Some manufacturers consolodate injectors, and just hope the O2 sensor does
the necessary adjusting.

I did rebuilt the regulator, but the sound doesn't seem to be coming
from there (I used a short piece of hose to trace the sound). If I
don't find anything with the fuel lines transfering noise, I'll pull
the cover off the fuel meter body and check out the regulator. The
injectors are brand new, and even with the old ones put back into it
the noise is still there. The inejectors in this TBI have always been
loud, but I've never had any noise in the cab before and now this
noise is louder in the cab than anywhere else. It's like chasing a
ghost around!
Thanks for the advice, it gives me one more place to look to possibly
solve this problem.

You can't, not right at the injectors. Best you can do is check it at
the back of the throttle body.
Normal failure for a pressure regulator is loss of pressure, not high
pressure. A restricted return line could conceiveably cause noisy
injectors due to high fuel pressure I suppose, but I'd think the high
pressure would be more likely to cause the thing to run rich rather
than just make the injectors noisy.
Could you have bent the trans dipstick tube up against the cab while
you were in there. My money is still on a grounded out line of some
kind, I've never heard an injector making *that* much noise.
How's the truck run, anyway?
--
Old Crow "Yol Bolson!"
'82 FLTC-P "Miss Pearl"
'95 YJ Rio Grande
BS#133, SENS, TOMKAT, MAMBM

You sure about that? All the TBI units I've had ran at 15 PSI.
And excessive line pressure won't make the engine run rich unless your
O2 sensor is broke.
It's probably the regulator, but I shouldn't even go that far until I
have an idea of what the noise sounds like. Is it a clicking? Buzzing?
Hissing? Without knowing what it sounds like I would have to say that
it could be a lot of different things. Once I had a really loud noise
that sounded like an exhaust leak from the carb but it turned out to
be nothing more than a crack in the PCV hose. A loose PCV valve can
make a lot of noise in the carb/TBI. The EGR valve and/or solenoid
might be messed up. The IAC valve might be broke or have a dirty
contact on the connector. There might be a manifold vacuum leaking
somewhere away from the TBI. All these can make sounds that seem to
come from the TBI (or carb). Just start unplugging stuff until you
hear something different.

The truck actually runs pretty normal, althouth twice it wouldn't
start only moments after being shut off (and then a couple of hours
later it did start). Until I figure out what's going on with it, I
don't trust it - and I depend a great deal on this truck. Using a
piece of hose to try to locate the source of the noise, it is loudest
inside the cab right at the firewall a few inches above the
accelerator where there is an unisulated piece of the cab sheetmetal.
on the direct opposite side, in the engine compartment, there is no
noise at all and there is literally nothing there. In the engine
compartment, the ONLY place there is a noise that is similair is right
at the injectors themselves. Even if the noise was being caused by a
problem with the regulator, PCV crack, vacuum leak, etc.. why would it
only be audible in the cab like that? I've had this truck for 12
years and have worked on almost every part of it at one time or
another, but this is really puzzling.

Questions:
What does it sound like?
Does the sound change (loudness and/or pitch) when you step on the
throttle?
Did you pull the hoses one by one in order to try and eliminate them
as a source?
Have you tried changing the heater controls on the dash (as ridiculous
as it may sound)?
What happens when you step on the brake?
Have you pulled the plug on the IAC?
And just for the heck of it, what's the voltage on the battery while
it's running?

A couple of people suggested seeing if fuel line was hititng the
cab... THANKS!! sure enough, one of the lines popped out of the
bracket and was sitting against the seam to the cab... so the injector
noise was transfering into the cab. I swear, if you heard the noise
you'd be certain it was someting serious!! thanks again.
one last issue I'm hoping this group can help me with. the last time
I was home, I backed the truck out of the shop (after looking and
looking and looking for this noise). after about an hour I went to
move it, and it wouldn't start. 3 hours later, it fired right up? my
truck has been the most reliable vehicle on the road in the 12 years
I've had it, but then this last April it broke down on a cross-state
trip. turned out to be the ICM. a month later, broke down again and
turned out to be the pick-up coil. a month later, intermittent
injector problems so I replaced both injectors and the ECM (with a
gasket set for the TBI including a diaphram for the regulator).
any ideas on this last issue? I wish I'd asked this group about that
crazy noise before wasting so many house hunting for it!!!
thanks again! one HUGE headache solved!... one to go.

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